This invention relates to valves for dispensing viscous products contained in a can or container in general, and more particularly to such a valve which has a seat at its tip to prevent hardening of the material which is left within the valve stem after dispensing.
Aerosol containers are being used increasingly for the dispensing of viscous products like cheese, whipped cream and other food products along with materials such as toothpaste and glues. Typically, the type of valve mechanism used in these devices is one in which a dispensing nozzle mounted atop the can is tilted in order to open a valve mechanism to permit liquid to flow out through the nozzle. Such a valve is more practical for dispensing viscous liquids than valves typically used to dispense non-viscous liquid or powder products which valves are of a smaller size containing small ports and are operated through axial movement. Other types of material such as toothpaste and also cheeses and the like, are dispensed from collapsible tubes with the pressure for forcing the material out of the tube being applied by the user externally thereto in well known fashion. Typically, these types of dispensers are not fitted with a valve but with a screw-on cap. However, should the cap become misplaced, the material will then harden at the entrance of the tube, causing difficulties and waste of product. In aerosol containers having the type of dispensing valve described above, one of the major problems, particularly when dispensing viscous material, is that material can be left behind in the nozzle, which material tends to harden and block the passages therein. In addition, when dispensing food products, such hardening of the materials can make the product unappetizing in addition to making it unsanitary and possibly harmful. In view of this, various mechanisms have been developed to overcome this problem. In one of these disclosed in U.S. Pat. No. 3,506,165, a valve is shown wherein the sealing of the valve occurs at the tip of the nozzle. This arrangement prevents hardening within the nozzle. However, it has a number of disadvantages since sealing at the end of the nozzle is not as easily accomplished as sealing at the bottom. Another proposed solution to this problem is disclosed in U.S. Pat. No. 3,489,323. The valve therein includes a sliding outer member which permits rinsing to remove any material which is left behind.
Although these prior art valves have been somewhat successful, they do not completely solve the problem associated with dispensing this type of material, particularly due to problems associated with tip sealing. Furthermore, none of these prior art devices have dealt with the problems associated with dispensing toothpaste and the like from collapsable tubes. Thus, there is a need for a type of tip seal which may be used with both aerosol valve dispensers and furthermore, with collapsable tube dispensers which protects the product which remains within the valve nozzle or the tube exit portion.